The technical field of the invention is the control of combustion in an internal combustion engine and more particularly the control of the fuel injection into an internal combustion engine provided with exhaust gas recirculation.
The standards relating to the emissions of pollutants are imposing an increasingly fine control on combustion and on the air intake circuit of the internal combustion engines, notably via the control of the exhaust gas partial recirculation circuit (EGR), and the various units situated upstream and downstream of the internal combustion engine. The emissions of pollutants are directly linked to the relative quantities of air and fuel taken into the internal combustion engine. The knowledge and the control of this parameter are thus important in order to reduce the emissions of pollutants.
The relative quantities of air and fuel taken into an internal combustion engine are characterized by the richness parameter. This parameter depends on the ratio between the mass of fuel and the mass of fresh air taken in.
In order to further reduce the consumption of fuel and the emissions of pollutants, an exhaust gas partial recirculation circuit is used, which alters the ratio between the fuel and the fresh air taken in. However, the value of the parameter obtained by calculation or measurement takes into account only the fresh air contributed by the intake circuit. The oxygen and unburned hydrocarbons contributed by the exhaust gas partial recirculation circuit are therefore disregarded.
The patent application FR 2 851 014 describes a calculation method that takes into account the fresh air coming from the exhaust gas partial recirculation circuit.
However, there is currently no determination device or method that makes it possible to take into account the contribution of unburned hydrocarbons by the exhaust gas partial recirculation circuit. Such a method would make it possible to determine the quantity of hydrocarbons brought by the exhaust gas partial recirculation circuit and accordingly reduce the quantity of fuel injected.